Method for forming channels in thermoplastic materials



Dec. 23, 1952 P. A. WILLIAMS 2,622,279

METHOD FOR FORMING CHANNELS IN THERMOPLASTIC MATERIALS Original Filed March 17, 1949 Patented Dec. 23, 1952 TENT OFFICE METHOD FOR FORMING CHANNELS IN- THERMOPLASTIC MATERIALS Paul A. Williams, West SenecaQN. Y.,-assi gnor to. Glenn Confections, Inc., Buffalo, N. Y.

Original application March 17; 1949, Serial No.

81,894.- Divided and this application April 25,

1 1 eam- 229.

7 a ms- This invention relates to the. formation of channels or grooves in the surfaces of objects formed of thermo-plastic materials. More particularly the invention relates to .theflmanufacr ture of whistles of thermo-plastic materials, such as of wax, paraffin or wax or paraffincontaining materials. Such whistles are commonly'made by flush molding and are hollow.

This application is a division of 'my copending application Serial No. 81,894, filed March 17, 1949, now U. S. Patent'No'. 2, 8 2;368;

An object of the invention is to provide an improved method for forming channels'in the surfaces of hollow articles-of thermo plastic materials, by which the channels'may'be-formed more or less automatically and uniformly without imosing forces on the materials whichmight-tend to tear or fracture'them, or leave burrededges.

Another object of the invention is to provide an improved method for making h'ollow whistles or similar objects of thermo-plastic materials; with which the whistle vent openings may be uniformly formed without danger of tearing the relatively thin walls of the whistle shell, and without clogging any of the chambers or passages; and which will provide-smooth and accurately formed edges at the whistle vent opening, sufficiently accurate to give uniform soundswh'e'n the whistle is blown.

A further object of theinvention is to provide improved methods for accomplishingthe above object and which will be somewhatautomatic, rapid. and inexpensive.

Other objectsand advantages will be apparent from the following description-'of one embodiment of the invention, and the novelfeatures-will be particularly pointed out-hereinafter -'incon-" nection with the appended claims;

In the accompanying drawing:

Fig. 1 is a plan of aportion of apparatus constructed in accordance with :this invention for forming the channel in whistles or-other objects of thermo-plastic materials} Fig. 2 is a transverse; sectional elevation through a mold in which hollow whistl'es.-are

formed by flush molding, before the whistle'vent openings are formed anfdbeforethefwhistles are removed fromthe mold;

Fig. 3 is a transverse, sectional-elevation through the apparatus shown inl igrl, the section being taken approximately' along the-- line 3-3 of Fig. 1;

Fig. 4 is another sectional elevation-through the same, the section.being..taken.-approximately along.the.line..4'4, 'of Fig. 1;

Fig. 5 is asimilar ltransverse ,;sectiona1:eleva- 2 tion through a portion of the same, the section being. taken approximately along the line 5-55 of'Fig. l'after the'whistle' has reachedthe por tion of .the' apparatus at the section line 5 -35; and

Fig. 6 is a side elevation of a' flush'moljded whistle with a whistle vent formed in this manner. 7 I

In the illustrated embodiment of theinvention, ahollow whistle l of suitable thefr'mo plastic materials or waxes'is shownin side elevationin Fig. {i'inv completed form. These whistles are first molded without the whistle vent opening 2, in a moldof'the type shown in Fig. 2. Referring to Fig- 2, them'old is formed of complemental mold sections 3 and 4 which'abut face to face along a parting lirre 5, and there are a plurality of mold cavities" Warr'anged side by side but slightly spaced apart in a row along themold formed' of the sections 3"and l. 2

These mold sections have between them at the parting line,an opening-l leading to each chamher in which a whistle is tobe formed through which molding wax in fluid condition may beintroduced and excess removed as usual in flush molding, and flanges Sand 9 extend along the sides of the mold at the face having opening 1, 50 that when the mold as shown in Fig. 2 isrotated clockwise a quarter revolution'to bring the opening l'uppermost, one maypour w'ax orother merino-plastic material into the mold, and the flanges 8" and 9 act like a funnel toprevent spreading of the fluid wax. The heated waxcor'igealswhere itcontact's' the metal walls 'of'the mold thatdefine the whistle chamber. After the wax or thermo-plastic material has congealed, by cooling, to the desired thickness, the mold is inverted so that the unconge'aled waxes or molding material may drain out, leaving thehollow shell that forms the whistle body. The mo'ld'setions3 andc maythen be separated, and since the'larger part of the cavity is within the section 3,.the molded shells will remain in thesection' t, with the part'thereof which was formerly in the molded section 4 projectingfrom the section 3. These whistle shells have'a stem'lt extending therefrom;.which serves'as a mouth piece, and thisystem; is provided with an air passage .l I, see Fig. 2,.from end to end.

'Tonform this ;,air,passage, a plate l2 extends along and overlieslthermold sections 3 and .4, as shown: in Fig. 2, I andtongues' 13 extend therefromain'to the mold chambers, one for each chamber, at the opening thatmolds the mouth pieces These tongues 13 are tapered toward their free ends so that after the wax'or molding materials have congealed around them and the excess uncongealed molding material has been drained out, the plate I2 may be removed with its attached tongues I3 leaving the passages II. It will be observed from Fig. 2 that since the free ends of the tongues I3 project into the space of the molding chamber, the wax or molding material will congeal around the free ends, and as a result the inner ends of these air passages I I will be closed. These closed ends of the air passages II are opened when the whistle sound openings are formed in accordance with this invention.

Referring next to Figs. 1, 3 and 4, I provide a frame I l and in this frame I mount a pair of pulleys I5 (only one being shown), which are spaced apart along the frame. A pair of endless belts I6 and I? pass around the pulleys I5 and are arranged side by side and spaced apart on the pulleys so as to provide a gap or space I8 between them. The upper runs or stretches of these belts I6 and Il are generally horizontal and extend side by side, but spaced apart, and travel at the same speed in the same direction. A rail I9 is disposed between the upper stretch of the belt I5, and this run or stretch rides on the horizontal, upper face or surface of the rail 19 and is supported thereby from sagging. A similar rail 20 slidingly supports the upper stretch of the belt I! and prevents it from sagging,

The rails I9 and 20 are supported respectively on studs 2I and 22 which pass through the frame I4 and are held in vertically adjusted positions by nuts 23 and 2 4, which are threaded on the studs 2I and 22 and engage opposite faces of the frame I4, as shown in Fig. 3. Thus, these rails I9 and 20 may be separately adjusted vertically to different heights and, consequently the heights of the belts I5 and I! in the upper runs or stretches may be determined. Inasmuch as the stem or mouth piece part of each molded whistle projects from mold sections a lot farther than the opposite side, the belt I! in its upper stretch is raised to a higher elevation, by its rail 20, than the belt I6,

and this difference in levels of the belt stretches I6 and I? is maintained for a substantial distance.

Disposed between the rails I 9 and 20 is a steam pipe 25 which is supported on studs 26 that depend therefrom and pass through apertures in the frame I 4 and are held at different adjusted positions in the frame is by nuts 21 and 23 that are threaded on the stud 2'5 and engage opposite faces of the frame It. This pipe 25 is connected at one end to a source of steam, not shown, so that this pipe 25 will be heated, although other means of heating it, such as by an electric resistance, may be employed if desired. This pipe 25 is disposed approximately horizontally between the rails 19 and 20, so as to extend in the direction of travel of the belts.

Welded or otherwise secured on the pipe 25 is a fin or rib 29 which has an upwardly tapered, sharp edge, something like an inverted V in shape. This rib 29 runs lengthwise of the pipe 25 and is progressively higher towards one end, that is, it increases in height from the pipe 25 progressively in the direction of travel of the upper stretches of the belts I6 and H, This rib or element 29 rises to progressively greater extents through the space between the belts in the direction of travel of the belts, for a purpose which will appear presently.

The rails I9 and 26 have upstanding, marginal guides or flanges 30 and 3I, disposed at intervals therealong, Fig. 4 which extend short distances along the sides of the belts resting on the rails, and prevent sidewise movements of the belts while on the rails. The frame I4 also has a guide arm 32 supported therefrom by arm 33. Arm 32 extends parallel to and above the rail I9, so as to serve as a placement guide for the mold section 3, as will be explained presently.

After a plurality of hollow whistles have been formed in the mold sections 3 and 4, as shown in Fig. 2, the plate 12 is first removed with its tongues I3, and then the mold section 4 is removed or separated, which leaves the hollow molded whistle shells extending somewhat from the sections 3, as shown in Fig. 4. The section 3 is then disposed, inverted, over the belts I6 and I1 with a side of the mold section 3 abutting against the guide rail 32, as shown in Fig. 3, and with the whistle shells resting on the belts I6 and I1, also shown in Fig. 3. The mold section 3 keeps the whistle shells properly positioned and spaced, and as it and the whistle shells are carried along by the belts I6 and I1, thelower end of the tapered apex or edge of the heated rib 29 will first engage with the whistle shells, because the rib gradually rises through the gap between the belts in the direction of travel of the belts.

As the whistle shells are carried along they will meet and engage with this'heated rib 29. The movement is relatively slow, so that the rib may melt away the wax or moldin material of the whistle shells with which it engages, and as the wax or molded material is melted by the heated rib 29, it drains away down the sides of the rib 29. The rib 29 will thus relatively rise into the moving whistle body and melt away an opening therein, as shown in Fig. 5, and in doing so, it forms the V-shap'ed whistle vent opening 2 in the molded whistle shell that opens into the chamber of the hollow whistle shell and also opens the inner end of the air passage I I. It also forms a sharp edge or corner 35 in the whistle shell, in proper position relatively to the air passage I I, so that an air column moving along the passage I i into the whistle body will be set into vibration after it strikes the edge 35, as is well known in whistles. After the whistle shells have moved past the rib 25, the mold section 3 may be lifted and then the whistle shells removed'from the mold section 3. They are then ready for use.

It will be observed that since the channels 2 are formed in the molded bodies in their lower faces, the melted wax or molding material will drain away and not plug the air passage II. If one cuts the whistle opening with a cutter, it may leave on the cut edge a fuzzy or burr edge at the end of the air passage, that spoils the whistle effect by causing improper and undesired eddy currents in the air column or stream. When the whistle vent opening is formed by melting, it gives a clean edge, free of burrs or fuzzy edges. Since the molded shell is above the heated rib that melts the channel therein, the wax which is melted will drain down the sides of the heated rib, because the heated rib keeps the wax that is in contact with it fluid, instead of forming ribs along the melted channel.

It will be understood that various changes in the details, materials and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

I claim: 7

1. The method of making whistles of molding wax which comprises first flush molding a hollow whistle body of said wax with a stem and an air passage in the stem, and then melting out a whistle vent opening in a wall of said body to intersect and open the inner end of said air passage.

2. The method of making whistles of molding wax which comprises first flush molding of said wax, a hollow whistle shell with an air chamber, a stem, and an air passage in said stem leading from its outer end nearly to but short of intersection with said chamber, and then melting a whistle vent opening into said shell to intersect said chamber and the inner end of said air passage.

3. The method of making whistles of molding wax which comprises first flush molding of said Wax, a hollow whistle shell with an air chamber, a stem, and an air passage in said stem leading from its outer end nearly to but short of intersection with said chamber, and then slowly inserting a heated wedge-shaped element into said shell to intersect said chamber and the inner end of said air passage to form a whistle vent.

4. A method of making whistles of molding wax which comprises first flush molding, of said wax, a hollow whistle shell with an air chamber, a stem, and an air passage in said stem leading from the outer end of the stem nearly to but short of intersection with said chamber, then holding the shell with that face in which a whistle vent is to be provided downwardly, and slowly melting a whistle vent upwardly into said shell to intersect said chamber and cross the inner end of said air passage.

5. The method of making whistles of molding wax which comprises first molding, of said wax, a hollow whistle shell with an air chamber, a stem, and an air passage in said stem leading from the outer end of the stem nearly to but short of intersection with said chamber, then holding the shell with the face in which a whistle vent is to be provided downwardly, causing relative movement of said shell lengthwise along, and with its said face in contact with the top of a heated rod with an upstanding tapered edge, and progressively causing relative approach of said tapered edge and said face during said relative movement to slowly melt a whistle vent opening in said face intersecting said chamber and said air passage.

6. The method of converting molding wax into whistles of the type having a hollow wax shell with an air chamber, a stem, an air passage in said stem leading from the outer end of said stem to said chamber, and an air vent opening into said chamber, in close proximity to the inner end of said air passage, which comprises first flush molding said wax into a hollow shell, in a sectional mold body, with a cavity corresponding to the outside dimensions of said whistle and having a removable core corresponding in size, shape and position to said air passage, and also having a removable wall for said cavity and covering that face of said molded shell in which the air vent is to be formed, and, while said molded hollow shell remains in the remainder of the mold body, first removing said core and said removable wall to form said air passage and expose the face area of that wall of said molded shell in which said air vent is desired, and then moving a heated tool into said exposed face area of said exposed shell wall, and against the shell wall closing the inner end of said air passage, to melt said air vent into the molded shell and melt off the wall closing the inner end of said air passage so as to open that passage into the air chamber in said shell.

'7. The method of converting molding wax into whistles of the type having a hollow wax shell with an air chamber, a stem, an air passage in said stem leading from the outer end of said stem to said chamber, and an air vent opening into said chamber in close proximity to the inner end of said air passage, which comprises first flush molding said wax into a hollow shell, in a sectional mold body, with a cavity corresponding to the outside dimensions of said whistle and having a removable core corersponding in size, shape and position to said air passage, and also having a removable wall for said cavity and covering that face of said molded shell in which the air vent is to be formed, and, while said molded hollow shell remains in the remainder of the mold body, first removing said core and said removable wall to form said air passage and expose the face area of that wall of said molded shell in which said air vent is desired, and then moving a heated tool laterally across and through said exposed shell wall, into said chamber to melt said vent opening into said exposed shell wall, and also across the wall defining the air passage within said air chamber to open the inner end of said passage approximately at the vent opening.

PAUL A. WILLIAMS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 229,163 Mills 1- June 22, 1880 1,049,701 Goonley Jan. 7, 1913 2,107,981 Ford Feb. 8, 1938 2,485,769 Phelps Oct. 25, 1949 

